It was nice to come upon this post, Rich Mayer has some compelling research on this topic and when studying him during my grad cert program at UF, I picked him as an educational psychologist to study for a project. His theory of multimedia design is really intriguing and after learning about him and the principles, I definitely put some of those to work in my design strategies (and also stopped doing some things that he found to be ineffective).
In my most recent class (Designing Integrated Multimedia Environments), interestingly my professor didn't disparage Myer in any way but he did want to point out to me a criticism of Mayer about which to be aware, I suppose to keep it in perspective. The criticism seemed to be regarding how authentic the trails or learning environments were. I keep that in mind but still think a lot of his principles make sense to keep in mind.